In order to diagnose a disease it is often necessary to examine tissue samples at high magnification. By locating and identifying anomalous features in a tissue sample, a pathologist can make a diagnosis, help the patient's physician select appropriate treatment and provide information on the efficacy of previous treatments. Pathologists are therefore critical to the diagnosis and treatment of many diseases.
In general, pathologists often work at locations geographically distant from the hospital or clinic at which a tissue sample is taken. In the past it was necessary to physically transport a tissue sample from the location of the patient to the pathologist, for example by express mail or courier. A pathologist would then prepare a slide specimen from the tissue sample and examine it under a microscope. However, physically transporting the tissue sample to the pathology laboratory may be time consuming, particularly if the patient is in a rural or remote area. Furthermore, if the tissue sample crosses a border, it must be inspected by customs officials. Finally, in many areas such as third world countries there simply are not many pathologists, thereby making it necessary for pathologists to spend an inordinate amount of time travelling to different facilities. For patients who require immediate diagnosis, this is a serious drawback.
The advent of digital pathology helped to alleviate this problem. In digital pathology, a high resolution digital scan of a slide is taken and this image is electronically transmitted to the pathologist for analysis. A physician or technician can prepare slides from tissue samples and create high resolution scans for off-site analysis by the pathologist. Furthermore, high volume slide scanners may scan dozens of slides per scanning operation. Thus, dozens of different slide specimens from one or more nearby medical facilities may be sent to a single location with a high volume slide scanner where digital images or “virtual slides” are created. These virtual slides are then electronically transmitted to appropriate pathologists over a computer network such as the internet.
Thus, digital pathology and high volume slide scanners have helped streamline pathological analysis by creating a hub to which all physical slides in a region may be sent. The high volume scanner at the hub is then used to electronically distribute virtual slides to pathologists anywhere in the world almost instantly. In other words, it is no longer necessary to send individual slides to pathologists in a number of specialized fields. Instead, all slides may be sent to the location of the high volume slide scanner, which is typically relatively near the medical facility where the tissue sample was taken compared to the location of the appropriate pathologist
However, although digital pathology with high volume slide scanners is an improvement over older pathology methods, it is not without drawbacks. First, existing high volume slide scanners are very large and expensive, often costing several hundred thousand dollars. This cost may be prohibitive, particularly in less wealthy countries and/or rural areas. Additionally, high volume scanners are generally loaded with slides only once a day. If an anomaly is found in a particular slide, it cannot be immediately removed or rescanned at a higher resolution for more detailed analysis. Further, high volume scanners are typically allotted to physicians only as workload allows so a physician may have to wait one or more days before it is possible to scan a new slide.
Finally, another drawback to conventional digital pathology is that very high demands are placed on the computer acquiring the image from the scanner. The acquired images are typically several gigabytes in size, and thus a powerful computer is required to quickly process, manipulate and analyze the images. These computers are generally very expensive, making the combination of a high volume slide scanner and acquisition computer cost prohibitive for many facilities.
In summary, high volume scanners are helpful for streamlining digital pathology and handling a large number of slides at once, but there remains a need for a smaller, more affordable, more flexible and more responsive digital pathology system.